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	$159.95	4.767%	$167.5748	$167.57	$167.55	$167.60
Purchase #2	$35.61	4.239%	$37.1195	$37.12	$37.10	$37.10
Purchase #3	$78.43	8.591%	$85.1679	$85.17	$85.15	$85.20
Purchase #4	$152.84	6.450%	$162.6982	$162.70	$162.70	$162.70
Purchase #5	$235.49	13.791%	$267.9664	$267.97	$267.95	$268.00
Purchase #6	$171.95	7.830%	$185.4137	$185.41	$185.40	$185.40
Purchase #7	$120.51	5.837%	$127.5442	$127.54	$127.55	$127.50
7 purchase totals =	$954.78		$1,033.4847	$1,033.48	$1,033.40	$1,033.50