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	$56.29	10.373%	$62.129	$62.13	$62.15	$62.10
Purchase #2	$248.81	13.157%	$281.5459	$281.55	$281.55	$281.50
Purchase #3	$85.56	12.285%	$96.071	$96.07	$96.05	$96.10
Purchase #4	$122.83	6.788%	$131.1677	$131.17	$131.15	$131.20
Purchase #5	$156.68	11.560%	$174.7922	$174.79	$174.80	$174.80
Purchase #6	$240.46	9.827%	$264.09	$264.09	$264.10	$264.10
Purchase #7	$56.32	10.279%	$62.1091	$62.11	$62.10	$62.10
7 purchase totals =	$966.95		$1,071.9049	$1,071.91	$1,071.90	$1,071.90