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	$125.69	4.181%	$130.9451	$130.95	$130.95	$130.90
Purchase #2	$30.72	9.190%	$33.5432	$33.54	$33.55	$33.50
Purchase #3	$86.73	6.270%	$92.168	$92.17	$92.15	$92.20
Purchase #4	$159.77	9.521%	$174.9817	$174.98	$175.00	$175.00
Purchase #5	$109.27	3.351%	$112.9316	$112.93	$112.95	$112.90
Purchase #6	$155.72	11.265%	$173.2619	$173.26	$173.25	$173.30
Purchase #7	$90.87	11.739%	$101.5372	$101.54	$101.55	$101.50
7 purchase totals =	$758.77		$819.3687	$819.37	$819.40	$819.30