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	$167.32	7.839%	$180.4362	$180.44	$180.45	$180.40
Purchase #2	$130.55	6.499%	$139.0344	$139.03	$139.05	$139.00
Purchase #3	$40.38	3.497%	$41.7921	$41.79	$41.80	$41.80
Purchase #4	$211.74	5.677%	$223.7605	$223.76	$223.75	$223.80
Purchase #5	$10.56	5.762%	$11.1685	$11.17	$11.15	$11.20
Purchase #6	$238.70	10.819%	$264.525	$264.53	$264.55	$264.50
Purchase #7	$209.76	5.563%	$221.4289	$221.43	$221.45	$221.40
7 purchase totals =	$1,009.01		$1,082.1456	$1,082.15	$1,082.20	$1,082.10