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	$196.39	11.809%	$219.5817	$219.58	$219.60	$219.60
Purchase #2	$170.73	8.550%	$185.3274	$185.33	$185.35	$185.30
Purchase #3	$98.79	7.355%	$106.056	$106.06	$106.05	$106.10
Purchase #4	$6.59	10.190%	$7.2615	$7.26	$7.25	$7.30
Purchase #5	$214.27	9.193%	$233.9678	$233.97	$233.95	$234.00
Purchase #6	$183.89	8.860%	$200.1827	$200.18	$200.20	$200.20
Purchase #7	$126.85	4.519%	$132.5824	$132.58	$132.60	$132.60
7 purchase totals =	$997.51		$1,084.9595	$1,084.96	$1,085.00	$1,085.10