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	$141.55	7.616%	$152.3304	$152.33	$152.35	$152.30
Purchase #2	$115.43	10.370%	$127.4001	$127.40	$127.40	$127.40
Purchase #3	$138.42	5.827%	$146.4857	$146.49	$146.50	$146.50
Purchase #4	$53.65	10.590%	$59.3315	$59.33	$59.35	$59.30
Purchase #5	$68.32	3.839%	$70.9428	$70.94	$70.95	$70.90
Purchase #6	$60.97	5.557%	$64.3581	$64.36	$64.35	$64.40
Purchase #7	$200.88	5.420%	$211.7677	$211.77	$211.75	$211.80
7 purchase totals =	$779.22		$832.6163	$832.62	$832.65	$832.60