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	$32.73	8.244%	$35.4283	$35.43	$35.45	$35.40
Purchase #2	$203.35	9.812%	$223.3027	$223.30	$223.30	$223.30
Purchase #3	$99.53	3.607%	$103.12	$103.12	$103.10	$103.10
Purchase #4	$138.61	10.281%	$152.8605	$152.86	$152.85	$152.90
Purchase #5	$197.41	7.529%	$212.273	$212.27	$212.25	$212.30
Purchase #6	$179.43	9.564%	$196.5907	$196.59	$196.60	$196.60
Purchase #7	$194.99	5.103%	$204.9403	$204.94	$204.95	$204.90
7 purchase totals =	$1,046.05		$1,128.5155	$1,128.51	$1,128.50	$1,128.50