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	$134.38	13.451%	$152.4555	$152.46	$152.45	$152.50
Purchase #2	$196.70	7.219%	$210.8998	$210.90	$210.90	$210.90
Purchase #3	$140.74	9.708%	$154.403	$154.40	$154.40	$154.40
Purchase #4	$205.88	13.797%	$234.2853	$234.29	$234.30	$234.30
Purchase #5	$28.90	4.643%	$30.2418	$30.24	$30.25	$30.20
Purchase #6	$240.77	5.202%	$253.2949	$253.29	$253.30	$253.30
Purchase #7	$24.73	4.498%	$25.8424	$25.84	$25.85	$25.80
7 purchase totals =	$972.10		$1,061.4227	$1,061.42	$1,061.45	$1,061.40