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	$188.51	4.322%	$196.6574	$196.66	$196.65	$196.70
Purchase #2	$18.67	4.500%	$19.5102	$19.51	$19.50	$19.50
Purchase #3	$111.93	13.602%	$127.1547	$127.15	$127.15	$127.20
Purchase #4	$86.67	12.192%	$97.2368	$97.24	$97.25	$97.20
Purchase #5	$204.47	5.216%	$215.1352	$215.14	$215.15	$215.10
Purchase #6	$115.66	11.240%	$128.6602	$128.66	$128.65	$128.70
Purchase #7	$150.74	10.487%	$166.5481	$166.55	$166.55	$166.50
7 purchase totals =	$876.65		$950.9026	$950.91	$950.90	$950.90