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	$89.72	7.615%	$96.5522	$96.55	$96.55	$96.60
Purchase #2	$36.26	12.749%	$40.8828	$40.88	$40.90	$40.90
Purchase #3	$61.41	7.216%	$65.8413	$65.84	$65.85	$65.80
Purchase #4	$67.81	5.415%	$71.4819	$71.48	$71.50	$71.50
Purchase #5	$11.47	12.344%	$12.8859	$12.89	$12.90	$12.90
Purchase #6	$198.88	9.797%	$218.3643	$218.36	$218.35	$218.40
Purchase #7	$216.42	11.236%	$240.737	$240.74	$240.75	$240.70
7 purchase totals =	$681.97		$746.7454	$746.74	$746.80	$746.80