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	$146.63	10.281%	$161.705	$161.71	$161.70	$161.70
Purchase #2	$43.68	4.129%	$45.4835	$45.48	$45.50	$45.50
Purchase #3	$37.69	4.444%	$39.3649	$39.36	$39.35	$39.40
Purchase #4	$248.59	6.411%	$264.5271	$264.53	$264.55	$264.50
Purchase #5	$227.50	11.672%	$254.0538	$254.05	$254.05	$254.10
Purchase #6	$211.32	11.502%	$235.626	$235.63	$235.65	$235.60
Purchase #7	$71.55	8.331%	$77.5108	$77.51	$77.50	$77.50
7 purchase totals =	$986.96		$1,078.2711	$1,078.27	$1,078.30	$1,078.30