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	$148.66	7.428%	$159.7025	$159.70	$159.70	$159.70
Purchase #2	$80.55	11.832%	$90.0807	$90.08	$90.10	$90.10
Purchase #3	$36.85	11.206%	$40.9794	$40.98	$41.00	$41.00
Purchase #4	$107.83	4.280%	$112.4451	$112.45	$112.45	$112.40
Purchase #5	$180.47	4.123%	$187.9108	$187.91	$187.90	$187.90
Purchase #6	$209.52	11.494%	$233.6022	$233.60	$233.60	$233.60
Purchase #7	$218.56	4.573%	$228.5547	$228.55	$228.55	$228.60
7 purchase totals =	$982.44		$1,053.2754	$1,053.27	$1,053.30	$1,053.30