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	$158.92	6.617%	$169.4357	$169.44	$169.45	$169.40
Purchase #2	$144.62	5.631%	$152.7636	$152.76	$152.75	$152.80
Purchase #3	$189.70	11.476%	$211.47	$211.47	$211.45	$211.50
Purchase #4	$194.34	3.236%	$200.6288	$200.63	$200.65	$200.60
Purchase #5	$38.83	4.718%	$40.662	$40.66	$40.65	$40.70
Purchase #6	$203.27	4.352%	$212.1163	$212.12	$212.10	$212.10
Purchase #7	$36.86	4.414%	$38.487	$38.49	$38.50	$38.50
7 purchase totals =	$966.54		$1,025.5634	$1,025.57	$1,025.55	$1,025.60