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	$24.83	5.432%	$26.1788	$26.18	$26.20	$26.20
Purchase #2	$35.38	6.334%	$37.621	$37.62	$37.60	$37.60
Purchase #3	$222.75	3.774%	$231.1566	$231.16	$231.15	$231.20
Purchase #4	$45.66	11.525%	$50.9223	$50.92	$50.90	$50.90
Purchase #5	$93.73	13.169%	$106.0733	$106.07	$106.05	$106.10
Purchase #6	$224.56	8.576%	$243.8183	$243.82	$243.80	$243.80
Purchase #7	$55.32	7.460%	$59.4469	$59.45	$59.45	$59.40
7 purchase totals =	$702.23		$755.2172	$755.22	$755.15	$755.20