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	$162.53	7.815%	$175.2317	$175.23	$175.25	$175.20
Purchase #2	$11.81	3.688%	$12.2456	$12.25	$12.25	$12.20
Purchase #3	$66.92	7.849%	$72.1726	$72.17	$72.15	$72.20
Purchase #4	$213.30	4.790%	$223.5171	$223.52	$223.50	$223.50
Purchase #5	$40.69	11.665%	$45.4365	$45.44	$45.45	$45.40
Purchase #6	$224.98	11.610%	$251.1002	$251.10	$251.10	$251.10
Purchase #7	$109.59	13.553%	$124.4427	$124.44	$124.45	$124.40
7 purchase totals =	$829.82		$904.1464	$904.15	$904.15	$904.00