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	$69.40	3.659%	$71.9393	$71.94	$71.95	$71.90
Purchase #2	$64.60	5.183%	$67.9482	$67.95	$67.95	$67.90
Purchase #3	$218.47	8.353%	$236.7188	$236.72	$236.70	$236.70
Purchase #4	$59.27	10.469%	$65.475	$65.48	$65.50	$65.50
Purchase #5	$239.63	9.820%	$263.1617	$263.16	$263.15	$263.20
Purchase #6	$53.84	10.231%	$59.3484	$59.35	$59.35	$59.30
Purchase #7	$201.54	6.142%	$213.9186	$213.92	$213.90	$213.90
7 purchase totals =	$906.75		$978.5100	$978.52	$978.50	$978.40