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	$174.70	12.608%	$196.7262	$196.73	$196.75	$196.70
Purchase #2	$187.88	3.805%	$195.0288	$195.03	$195.05	$195.00
Purchase #3	$52.56	10.857%	$58.2664	$58.27	$58.25	$58.30
Purchase #4	$171.72	9.355%	$187.7844	$187.78	$187.80	$187.80
Purchase #5	$85.49	5.595%	$90.2732	$90.27	$90.25	$90.30
Purchase #6	$153.81	7.629%	$165.5442	$165.54	$165.55	$165.50
Purchase #7	$91.26	10.280%	$100.6415	$100.64	$100.65	$100.60
7 purchase totals =	$917.42		$994.2647	$994.26	$994.30	$994.20