Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$219.28	11.428%	$244.3393	$244.34	$244.35	$244.30
Purchase #2	$123.61	12.490%	$139.0489	$139.05	$139.05	$139.00
Purchase #3	$166.89	11.167%	$185.5266	$185.53	$185.55	$185.50
Purchase #4	$133.49	5.614%	$140.9841	$140.98	$141.00	$141.00
Purchase #5	$120.29	12.640%	$135.4947	$135.49	$135.50	$135.50
Purchase #6	$183.83	3.594%	$190.4369	$190.44	$190.45	$190.40
Purchase #7	$151.77	5.854%	$160.6546	$160.65	$160.65	$160.70
7 purchase totals =	$1,099.16		$1,196.4851	$1,196.48	$1,196.55	$1,196.40