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	$189.43	11.319%	$210.8716	$210.87	$210.85	$210.90
Purchase #2	$34.41	9.538%	$37.692	$37.69	$37.70	$37.70
Purchase #3	$113.95	11.770%	$127.3619	$127.36	$127.35	$127.40
Purchase #4	$196.33	10.471%	$216.8877	$216.89	$216.90	$216.90
Purchase #5	$163.83	6.364%	$174.2561	$174.26	$174.25	$174.30
Purchase #6	$180.35	4.573%	$188.5974	$188.60	$188.60	$188.60
Purchase #7	$64.95	5.130%	$68.2819	$68.28	$68.30	$68.30
7 purchase totals =	$943.25		$1,023.9486	$1,023.95	$1,023.95	$1,024.10