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	$112.44	11.492%	$125.3616	$125.36	$125.35	$125.40
Purchase #2	$242.57	4.251%	$252.8817	$252.88	$252.90	$252.90
Purchase #3	$41.61	4.337%	$43.4146	$43.41	$43.40	$43.40
Purchase #4	$93.58	7.669%	$100.7567	$100.76	$100.75	$100.80
Purchase #5	$101.27	7.702%	$109.0698	$109.07	$109.05	$109.10
Purchase #6	$99.35	11.786%	$111.0594	$111.06	$111.05	$111.10
Purchase #7	$37.66	10.790%	$41.7235	$41.72	$41.70	$41.70
7 purchase totals =	$728.48		$784.2673	$784.26	$784.20	$784.40