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	$173.65	13.191%	$196.5562	$196.56	$196.55	$196.60
Purchase #2	$81.65	11.822%	$91.3027	$91.30	$91.30	$91.30
Purchase #3	$23.32	8.852%	$25.3843	$25.38	$25.40	$25.40
Purchase #4	$191.44	5.695%	$202.3425	$202.34	$202.35	$202.30
Purchase #5	$36.37	8.164%	$39.3392	$39.34	$39.35	$39.30
Purchase #6	$175.85	5.685%	$185.8471	$185.85	$185.85	$185.80
Purchase #7	$47.59	13.504%	$54.0166	$54.02	$54.00	$54.00
7 purchase totals =	$729.87		$794.7886	$794.79	$794.80	$794.70