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	$174.85	7.648%	$188.2225	$188.22	$188.20	$188.20
Purchase #2	$245.82	12.229%	$275.8813	$275.88	$275.90	$275.90
Purchase #3	$31.44	4.229%	$32.7696	$32.77	$32.75	$32.80
Purchase #4	$111.81	11.316%	$124.4624	$124.46	$124.45	$124.50
Purchase #5	$187.63	8.629%	$203.8206	$203.82	$203.80	$203.80
Purchase #6	$123.27	3.599%	$127.7065	$127.71	$127.70	$127.70
Purchase #7	$68.89	4.588%	$72.0507	$72.05	$72.05	$72.10
7 purchase totals =	$943.71		$1,024.9136	$1,024.91	$1,024.85	$1,025.00