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	$141.67	7.274%	$151.9751	$151.98	$152.00	$152.00
Purchase #2	$125.38	3.570%	$129.8561	$129.86	$129.85	$129.90
Purchase #3	$124.44	12.722%	$140.2713	$140.27	$140.25	$140.30
Purchase #4	$131.33	7.843%	$141.6302	$141.63	$141.65	$141.60
Purchase #5	$170.31	12.280%	$191.2241	$191.22	$191.20	$191.20
Purchase #6	$124.67	5.384%	$131.3822	$131.38	$131.40	$131.40
Purchase #7	$148.34	5.251%	$156.1293	$156.13	$156.15	$156.10
7 purchase totals =	$966.14		$1,042.4683	$1,042.47	$1,042.50	$1,042.50